THE PILOT IN COMMAND ATTEMPTED A WHEEL TAKEOFF FROM AN AREA USED FOR A SEAPLANE PULLOUT RAMP. WITNESSES SAID THEY HAD NOT SEEN A WHEEL PLANE ATTEMPT TAKEOFF FROM THAT SPOT IN THREE YEARS. THE AVAILABLE TAKEOFF DISTANCE WAS APPROXIMATELY 500 FEET. THE DHC2 BEAVER STRUCK A ONE STORY GENERATOR BUILDING, SHEARING OFF A HORIZONTAL STABILIZER. THE AIRCRAFT CONTINUED ONE MILE TO INT'L AIRPORT AND LANDED WITHOUT INCIDENT.